Rectifier control system



Aug. 10, 1937. D. JOURNEAUX 2,089,896

RECTIFIER CONTROL SYSTEM Original Filed April 29, 1933 3 Sheets sheet 1ug. 1937. D. JOURNEAUX 2,089,896

RECTIFIER 'CONTROL SYSTEM Original Filed April 29, 1933 3 Sheec Sheet 2Aug. 10, 1937.

D. JOURNEAUX RECTIFIER CONTROL SYSTEM Original Filed April 29, 1933 3Sheecs-Sheet 3 %IIIIII ml Patented Aug, 10, 1937 PATENT OFFICE BECTHIERCONIROL SYSTEM Didier Jumeaux, Wauwatosa, Wls., asslgnor toAllis-Chalmers Manufacturing Company, Milwaukee, Wia., a corporation cfDelaware Application April 29,

1933, Serial No. 668,498

Eenewed November 14, 1936 49 Clalms.

This invention relates to imprements in control systems, and moreparticularly to a system for limiting the current within an electrondischarge device to a value which the device is in condition to carry atthe instant considered, with out danger of damage thereto or of iaultyoperatien thereof.

It is.known that, in an electron discharge device 0! the vapor type inwhich the vapor is 1 supplied from the cathode material, the arc dropwithin the device depends upon the conditions of pressure andtemperature of the vapor carrying the arc. It is desirable to alwaysmaintain the arc drop at a low value because a high arc drop '15decreases the efliciency of the device, may cause deterloration ordestruction et the device by calized liberation of excessive heat,mavcause failu're of the control'electrodes to function and --may alsoresult in oscillations or other disturbances in the circuits associatedwith the device. The arc drop may reach an excessive value when thewalls of the device are too cold so that the vapor produced at thecathode condenses on the walls toc rapidly and does not leave asufiicieht 5 amount of vapor available for ionization in the arc path.Tire result of such condensation is that the electronic space charge isnot sufliiently neutralized by the amount of ionizable vapor present andthe arc drop reaches a value inter- 3o mediate that of a normallyoperating vapor device and that of a device ofathe vacuum type. Suchcondition may arise -When eooling means assoclated with the device areadJusted for maintaining the temperature-thereoi at tob low a value orelse when the device, alter carrying an amount ct current for which itstemperature ls adequate,

is suddenly required to carry a larger amount of current for which itstemperature is too low. It is then necessary either to disconnect thedevice from the associated circuits, or to provide a larger amount ofvapor wlthin the device, or to reduce the amount of current fiowingtherethrough to prevent the continued operation of the device underconditions producing a high arc drop. Such results can be obtained bymeans of a system responsive to the magnitude ot the arc drop, whichprterably utilizes voltage responsive means 'connected between one anodeand the cathode of the device over an auxiliary electron dischargedevice. The connections are then prat- -erabl'such as to; imp'ress thevoltage between qde and cathode of the device on the voltage ;,iep0nsivemeans only while the anode is carryv in: crrent. Under the mostfavorable operating fl 5 conditions, as in wellknown. the value of thearc drop normally varieswith the amount of current carried by the deviceand it is therefore advantageous to provide an automatic adjustment ofthe voltage responsive circuits in response to the amount of currentfiowing through the device.

It is thereiore among the objects of the present invention to provide acontrol system for electron discharge devices which system is responsiveto the variations of the magnitude of the arc drop within the device.

Another object of the present invention is to provide a control systemfor electron discharge devices which system is responsive to the peakvalue of the arc drop within the device.

Another object of the present invention is to provide a control systemfor electron discharge devices which system is responsive to the valueof the voltage between one anode and the cathode of the device onlyduring the periods when the anode is carrying eurrent.

Another object of the present invention is to provide a control systemfor electron discharge devices which system employs one or moreauxiliary electron discharge devices. v

Another object of the present invention is to provide a control systemfor electron discharge devices in which the system is automatica1lyvariably adjusted in response to the magnitude of the current flowingthrough the device.

Another object of the present invention is to provide a control systemfor electron discharge devices for interrupting the fiow of currentthrough the device when the arc drop Within such device reaches a valuegreater'than the normal operating value thereof.

Another object of the present invention is to provide a control systemfor electron discharge devices whereby the amount of vapor producedwithin the device may be increased when the arc drop within the devicereaches a value greater than the normal operating value thereof,

Another object of the present invention is to provide a control systemfor electron dscharge devices operable to regulate the floW of currentthrough the device in response to the variations et the arc drop withinsuch device.

Another object 01. the present invention is to provide a control systemfor electron discharge devices operaile to variably energize the controlelectrodes of the device in response to the variations of the arc dropwithin such device.

-Objects and advantages other than those above set fortin will beapparent irom the.following description when read in connection with theaccompanying drawings, in which:

Fig. 1 diagrammaticaily iliustrates one embodiment of thepresentinventian operable to disconnect an electron discharge device ofthe vapor type, which is operable as an alternating current rectifier,from the supply line thereof when the average arc drop within suchdevice exceeds, by a predetermined amount, the value of the arc drop ofan auxiliary device having the arc drop therein adjusted in response tothe value of the current flowing through the main device;

Fig. 2 diagrammatcally illustrates, the portions differing from theembodiment 01. Fig. 1. of a modified embodiment of the present inventiondifiering from the embodiment illustrated in Fig. 1 in that the amountof exciting current of the device is regulated in response to thevariations of the value of the arc drop and the device is notdisconnected from the supply line upon change in the arc drop;

Fig. 3 diagrammaticaily illustrates the modified portions of anothermodified embodiment of the present invention diflerng from theembodiment illustrated in Fig. 2 in providing means for supplying vaporto the device in response to the 2 variation of the arc drop within suchdevice;

Fig. 4 diagrammatically illustrates another embodiment of the presentinvention whereby the current within the device is regulated in.response to the variations of the peak value 01 30 the arc drop within thedevice;

Fig. 5 diagrammatically illustrates another embodiment of the presentinvention whereby the control electrodes of the device are variablyenergized, in response to the variation of the average arc drop, tocontrol the flow of current within such device;

Fig. 6 diagrammatically illustrates the modified portions 01 a modifiedembodiment 01 the present invention diflerlng from the embodimentillustrated in Fig. 5 in the method of connecting the voltage responsivecircuits Fig. 7 is a diagram of the voltage relations between one anodeand the cathode of the device illustrated in Figs. 1 to 4;

Fig. 8 is a diagram of the voltage between one anode and the cathode andof the voltage of a current transformer receiving the current of thesame anode of the device illustrated in Figs. 5 and 6;

Fig. 9 is a characteristic curve oi some of the auxiliary dischargedevices utilized in the ditferent embodiments illustrated; and Fig. 10diagrammatically illustrates another embodiment of the present inventionin which the control electrodes of the device are variably energized inresponse to the variations et the peak value of the arc drop within suchdevice.

Referring more particularly to the drawings by characters of reference,reference numeral il designates an alternating current line, hereinshown as a three phase line only for the reason that such type of lineis most frequently utilized in practice. Line il is utilized as a supplyline for an electron discharge device i6 connected therewith by means ofa transformer having a primary winding 12 and a secondary winding fl3.Winding i3 preerably' comprises a plurality of star connected portionsseverally connected With the anodes E4 015 device l6. Ihe cathode il ofof a direct current line having the second conductor l9 thereof.connected with a neutral point 75 66 may be interrupted by means of 8.circuit device i6 is connected with one conductcr i8 breaker 2l herenshoWn as being inserted in the connection between winding [2 and lineIl. It will be understood that such circuit breaker could also beinserted in the connections between winding l3 and anodes [4 or inconductors l8 and l9, opening of such circuit breaker resulting, in eachcase, in interruption of the flow of current within device l6. Circuitbreaker 2l tends to open under the action of a spring 22 and is normallyretained in the closed position by a latch 23 which may be released by asolenoid or trip coil 24.

For the purpose of obtaining a circuit responsive to the variations ofthe voltage between one anode M and cathode il, one"of such anodes isconnected through a battery 25 with the anode 26 of an electrondischarge device 21 having a cathode 28. .Device 21 is preferablv of thegas or vapor type and the operating vapdr therein may be supplied by adrop of mercury 29. Cathode 28 may be of the incandescent type heated bythe current of a battery 3l, such current being adjusted by means of arheostat 32. Cathode 28 is connected With conductor l8 over a rheostat33, a meter 34 and the coil 36 of a time delay relay 31. Relay 31 isoperable to close contacts 38 to connect a battery 39 With trip coil 24;current flowing in rheostat 33 and coil 38 may be fmeasured by theindicating cr recording-instrument 34. As is well known, the arc dropwithin a device such as device 21 is smaller than the arc drop withindevice l6, and also varies to a large extent in dependence upon thetemperature. The temperature of device 21 is preferably maintainedconstant by means of a heater 4l receiving 'current from a suitablesource such as battery 39, such current being controlled by a thermostatsuch as a bimetallic strip 42. A. rough adjustmnt of the current inheater 4l may be obtained by a rheostat 43. To 1egulate the flow ofcurrent through device 21 in response to the amount of current flowingthrough device i6, the operation of thermostat 42 may be controlled by asecond thermostat 44 maintainedat a variable temperature by heater 46energized in response to the value of current flowing through device I6by means of a shunt 41 in circuit in conductor l8.

In operation, assuming the system to be connected as'shown inFig. 1 andline Il to be encrgized, each of the anodes l4 cf device l6 receives analternating voltage from the associated portion 0i winding l3. Suchvoltage is represented in Fig. 7 by a curve 48 drawn with respect toline 49 representing the voltage of cathode i1 as the reference line. Aswill be seen from Fig. 7, the voltage represented by curve 48 ispositive and has an approximately constant value during the activeperiod et operation of anode M and ls variably negative during theidling period of such anode. In Fig. 7, the distance between line 49 andline 5l represents the arc drop within device 21 which drop may beconsidered as substantiaily constant even when such device receivesvariable currents, provided such currents are limited in value within apredetermined range. When the voltage represented by curve 48 is greaterthan the voltage represented by line 51, a pulsating current will :flowfrom anode i4 over bttery 25 and anode 26 to cathode.28 of device 21,over rheostt 33, meter 34, and coil 36 to conductor i8, in parallel withthe arc between anode M and cathode il. The magnitude oi? such currentis proportional to the cross hatched areas 52 in Fig. 7 and is dependentupon the average value of the arc drop between anode M and cathode i1represented by the positive ordinates o! curve 48. In the aboveconsideration, the voltage et the battery 25 was not taken into account.By adJusting 5 such voltage at a value substantiaily equal to thevoltage drop within device 21 and opposed thereto, the flow of currentthrough device 21 is substantially unaflected by such two voltages andis then substantially proportional to the entire areas bound by thepositive portions of curve 48 and also, thereiore, to the averagevoltage drop withindevice l5. Assuming that for any reason, the arc dropin device l8 increases over the value previoualy considered. suchincreased arc drop causing application of a higher potential to anode28, the current flowing from anode l4 over device 21 will increasecorrespondingiy and, upon reach- Inc a predetermined value, will cause0011 38 to attract armature of relay 31 to close contacts 88 thereof.Such closure is eflected, however, only if such flow of current iscmtinued over a predetermined period of time necessary for the operationof the time delay mechanism of relay 31. Such time delay is dasirable toprevent closure 01 contacts 38 upon occurrence of a transient increaseof the arc drop in device l5 which would' notnecessitate interruption ofthe operation of device I8.

If the increase of the arc drop considered above is commensurate with anincrease in the value of the current carried by device l6, such increasein the current will cause a.larger current to flow through heater 48,thereby causing thermostat 44 to move out et engagement with the contact5 cf thermostat 42. Thermostat 42 is thereby adjusted to maintain device21 at a temperature lower than previously obtained. The arc drop indevice 21 then increases as the temperature oi such device becomeslower, thereby maintain- 40 ing the flow of current therethrough at alow value and preventing the operation of relay 31. By means of thesystem illustrated, the flow of current through the device is thusinterrupted only when the arc drop within such device reaches 45 a valuewhich is in excess of a value commensurate with the value of the currentflowing through the device. As heater 45 and thermostat 44 are howevernecessarfly endowed with thermal inertia, the heating of thermostat 44by heater 46 cannot follow rapld variations et the current flowingthrough device 18 and shunt 41; If such current increases from arelatively low value to a relatively high value, thus causlng the arcdrop in device l8 to increase. at first the arc drop in 55 device 21remains adJusted to the initial value thereof.. 'If the rate of changeof the current in device l6 is relatively low, the response of theadjustment of the arc drop in device 21 by the action of heater 4|,although lagging behind the 0 change of current in device [8, is nevermateriaily diflerent from the steady state adjustment thereoi'. Ifhowever the rate et change of the current in device t8 15 relativelyhigh, as the result for example of a short circuit in line i8, l8, theoperation cf device 21 is completely readiusted in response to theincreased value of such current after a time delay such that, in themeanwhile, relay 81 may operate in response to the increase in 70 thearc drop in device l8. Devie I8 la thus protected against any damagewhich might be caused therein by the flow of short circuit currenttherethrough. In a general manner, the opention oi device 21 and,therefore.the operation of 7 relay 81 is variably adjusted in dependenceupon the rate of change of the flow of current through device l5.

In the embodiment partially illustrated in Fig. 2, it is assumed thatthe arc within device [6 is maintained by means of two excitation anodes53 supplied over fesistances 54 from an excitation transformer 58energized from line l I. The amount of excitation current flowingthrough device I5 is regulated by adjusting the amount of resistance inthe circuit of such excitation anodes, such resistance comprising afixed resistance 51 and resistance 58 which may be short circuited overcontacts 38 of relay,81. In the present embodiment, when the arc drop indevice l8 reaches a value greater than the normal value commensuratewith the value of the current flowing through such device, relay 31closes contacts 38 and thereby short circuits resistance 58. amount ofexcitation current flowing between excitation anodes 53 and cathode l1is thereby suddenly increased and results in the production 01 a largeramount of operating vapor from cathode l1. Such increased production ofvapor results in an increase of the vapor pressure within device l5which tends to reduce the arc drop within such device to the normalvalue thereof.

In the embodiment partialiy illustrated in Fig. 3, device l6 isassociated with a heating chamber 59 receiving operating materiai fromcathode l1. Chamber 59 is in communication with a vapor distributor 82conducting the operatlng vapor produced within such chamber to the spaceadjacent anodes l4, where such vapor escapes through openings 63 in pipe62. Chamber 59 is preierably heated by a heating resistance 6l energizedfrom battery 39 over contacts 38. When the arc drop within device I5reaches a value which is excessive according to the standard definedabove, relay 31 causes resistance to receive current from battery 39over contacts 38 thereby causing the production of vapor which isconducted in the space adjacent anodes I4. Such vapor is utilized forthe complete'ionization of the arc path, and the arc drop within device80 is thereby restored to the normal value thereof.

In the embodiment illustrated in Fig. 4, the flow of current throughdevice I6 is controlled by a plurality cf reactors 18, 19 and 8! whichmay be given variable values of inductance by saturation of the coresthereof by means of a plurality of direct current saturating windings14, 16 and 11. In the present embodiment, the current flowing throughdevice 21 is utilized for charging a condenser 64 connected betweencathode 28 and conductor l8. Rheostat 33 is then adjusted to a highValue so that the current fiowing over such rheostat between successivecycles of the voltage of line il does not appreclably decrease thecharge of condenser 64. Cathode 28 is connected with the cathode 69 ofan electron discharge device of the high vacuum type having the grid 66thereof connected with conductor l8 over a blas battery 12 and aprotective resistance 13. Cathode 69 is preferably of a. type similar tothat of cathode 28 and may be energized from battery 3l over a rheostat1l. The anode 58 of device 61 is connected with cathode 69 over 9.circuit including a plate battery 82, a rheostat 83 and coils 14, 16 and11. Such circuit may also include the resistance element 86 of a carbonpile regulator 84 having an operating solenoid 81 energized from shunt41 over a rheostat 89. The action of solenoid 81 is opposed by a spring88 as is weil known in the art. 1! the voltage between anode I4 andcathode l1 during the idling period of such anode. repre- The sented bythe negative portion of curve 48 Fig. 7, is greater than may be safelyapplied between anode 26 and cathode 28, a suitable device such as aglow tube 91 may be connected between 5 anode 26 and conductor 18. Suchdevice should be so selected as not to conduct current when recelvingthe arc drop between anode 14 and cathode 11, but to conduct currentwhen receiving the much larger negative voltage of anode 14 during theidling period. The current then flowing through device 91 is preferablylimited by a resistance 92. Such resistance does not appreclably affectthe charge of Condenser 64 provided that the ohmic drop caused withinsuch resistance by the current flowing over rheostat 33 be maintained ata negligible value.

In operation, during the idling. period of anode 14, device 91 carriescurrent and maintains anode 26 at a voltage which is negative withrespect to 30 the voltage of cathode 28 by tfie value of the dischargedrop within device 91. Device 21 therefore does not carry current duringsuch period. During the active period of anode 14, neglecting thecurrent flowing over rhostat' 33, it Will be seen that condenser 64 isgradually charged during the successive periods of current flow in anode14, at a rate depending upon the value of resistance 92. As shown inFig. 7 the arc drop shown by curve 48 usually presents a maximum or peak30 value during 9. portion of the current carrying period of the anode.When the arc drop reaches such valuecondenser 64 is chargedcorrespondingly, and as such .condenser cannot discharge over device 21,it will maintain its charge from one cycle to the next. The voltagebetween cathode 28 and conductor 18 is then represented by thedifierence of the ordinatescf line 92 passing .through the peaks ofcurve 48 and of line 51 representing the arc drop within device 21. As40 set forth above, the current flowing through resistance 33 is toosmall to cause condenser 64 to discharge appreciably between peaks ofcurve 48 but the flow of such current through device 21 tends tomaintain the arc drop therein et a 45 stable value. In addition,resistance 33 provides a. path for the partial discharge of condenser 64when the arc drop within device 16 changes from one value to another andlower value.

In Fig. 9, curve 99 represents the value of the 50 plate current ofdevice 61 plotted against the value of the grid voltage of such devicefor a predetermined value of the resistance in the plate circuit. In theembodiment illustrated in Fig. 4 it may be assumed that the voltage ofgrid 66 is negative 55 relative to the voltage of the cathode and isrepresented in magnitude by the distance 0A consisting oi the negativevoltage 0B et condenser 64 plus the voltage BA of battery12. The currentfiowing through coils '14, 16 and 11 is 60 then represented by ordinateAC of curve 911.

Assuming that the voltage drop in device 16 increases above the normalvalue thereof, condenser 64 becomes charged at a higher voltagerepresented in Fig. 9 by distance 0D and the voltage 85 of grid 66 isthen represented by distance 0E. The plate current oi device 61 isthereby reduced 'to the value EF so that the cores of reactors E8, 119and 81 become substantially desaturated. Such 4 reactors then introduce,in the circuit of device 16, &- voltage drop whlch causes the currentflowi ng through such device to be reduced to such an xtent that thevoltage drop again decreases to tle 'normal value thereof. If theincrease of the voltage drop is dueonly to an increase in the 75 currentof device l6, such in crease ci current will .ags of line 11.

"cause solenoid 81 to receive an lncreased cunent from shunt 41 therebyincreasing the pressure on carbon pile 86. The resistance in the circuitof coils 14, 16 and 11 is thereby decreased so that a current ofsufliientmle 'to saturate the cores.

nected portions of the secondary winding 96 of a control transformerhaving a primary winding 94 energized from line 11. .The controltransformer 94, 96 may be constructed as a phase shifter to permitregulation of the flow of currentwitlfin device 16. As is well known,such device may then operate as a rectifier to transmit power from line11 to line 18, 19, or as .an inverter to transmit power in the reversedirection. The energization of control electrodes 93 ls automaticallyadjusted by means of a regu-.

lator 98 operable to vary the resistance in the connections of winding94 with line 11.

The regulator is herein represented as being of the rocking sector typeand being actuated by.

an armature 99 mounted on a spindle 101. Ar-

'mature 99, which is movablebetween' the pole pieces of an electromagnetcore 102, is provided with a winding 163 which is connected in serieswith a winding 1114 of the electromagnet to impart a torque to sucharmature upon energization of the windings. The core also has a secondwinding 196 energized from shunt 41. The torque imparted to spindle 101is opposed by a spring 101 which prevents spindle 1111 from rotatingcontinuously and the tension of the spring is adjusted by a screw 168.Spindle 101 canies a hub 1119 serving as fulcrum for a plurality ofconductive sectors 111. Ea,ch sector is insulated from hub 1119 androcks on an arcuate contact path consisting of a plurality cf conductivesegments separated by insulation; each segment is connected withaportion of a tapped resistance 112. Tosimplify the drawing each sectoris however represented as being directly in contact with the associatedresistance. Each resistance 112 is connected between two conductors ofline 11 so that each sector 111 serves as a movable tap to impress, onwinding 94, voltages of variable phase with respect to the volt- Suchconnections permit shifting of the phase of energization of controlelectrodes 93 to thereby regulate the amount of current carried by theassociated anodes 14 as is well known in the art.

Assuming that device 16 is operating as a rectifier, curve 113 of Fig. 8represents the voltage between anode 14 and cathode 11 when the time ofoperation of anode 14 is delayed by the action of control electrode 93.Curve 113 includes portions GH over which the anode does not carrycurrent although its voltage is positive with respect to that of cathode11 and portions KL, over which the anode carries current, which aresimilar to the positive portions cf curve 48 in Fig. 7. The remainingportion LG is similar to the negative portion of curve 48. It will beseen that the system must be made respbnsive to the voltage betweenanode 14 and cathode 11 over portions KL of curve 113 and not overportions GH, over which such voltage may be of considerably greatermagnitude.

To obtain the :oove result grid 88'of device 61 must not be on 1stantlyoperatively connected with the anode 16 considered, as suchgrid wouldthen receive voltages corresponding to portion 5 GH of curve 113. Suchresult is avoided by connecting grid 61S, over resistance 13 and biasbattery 12, to resistance 92 already utilized in the embodimentillustrated in Fig. 4. In the present embodiment, for the reason thatthe positive voltage between anode and cathode of device 18 may becomevery great, it is no longer possible to use a device 91 which wouldcarry current during the positive period of anode 14 corresponding tocurveportion GH, and which would 15 thereafter continue to carry currentover the period corresponding to curve portion KL. Device 91 ispreferably replaced by a device 114 of the same type as device 21, whichmay carry current only during the negative period of anode 14. Duringthe period corresponding to portion GH, grid 66 receives through battery12, 8. voltage which is substantialiy the voltage of conductor 18 by theconnection of resistance 92 With the anode 124 of a device 121 similarto device 61. The cathode 126 of such device is connected with conductor18 and the grid 119 thereof is connected with cathode 126 over aresistance 123, a bias battery 122, and 3. portion of a rheostat 11T.Rheostat 111 is energized from a current transformer 116 insertedbetween winding 13 and anode 14. The plate circuit of device 81 isclosed over battery 82, rheostat 83 and colis 183 and 184, so that theposition of regulator 98 is determined by the average magnitude of theplate current in device 81.

As is well known the voltage impressed on rheostat 111 from currenttransformer 119 may be represented by a curve H8 referred to axis 113 inFig. 8. The voltage between grid 119 and cathode 126 may then berepresented, at a dltIer-.

ent scale, by the same curve-118 referred to another axis 128. Duringthe period corresponding to curve portion GH, grid 119 thus has aslightly negative voltage with respect to cathode 128, represented bypoint A in Fig. 9, and permits flow of current from anode 124 to cathode128. The voltage between anode 14 and cathode 11 then appears at theterminals of resistance 92 and the only potential applied on grid 68 isthat of battery '12, provided that the impedan'ce of device 121 be smallas compared with resistance 92. Such voltage may be represented bydistance 0M in Fig. 9, corresponding to the lower knee of curve 911. Atthe time corresponding to point H, K in Fig. 8.-thc voltage of currenttransformer 118 reverses so that the voltage of grid 119 reached a valuerepresented by point B sufiiciently negative to interrupt the flow ofcurrent through device 121. Grid 86 is then energized f 1om anode 14over resistance 92, battery 12 and resistance '13. The average voltageof grid 86 during interval KL is then represented by distance 0E in Fig.9 and the current fiowing through windings 1113 and 104 is representedby ordinate EF. If the arc drop within device 18 increases, the averagevoltage of grid 66 becomesless negative and reaches a value representedby 0A for which the current in windings 193 and 184 is represented byordinate AC. Regulator 98 therefore rotates in such 70 3. direction asto retard the time of positive energization of control electrodes 93,thereby causing the current within device 16't0 decrease to an extentsufllcient to reduce the average arc drop to the normal value thereof.If the increase of arc drop was caused by an increase of current,

winding 1118 receives an increased current from shunt 41 therebyopposing the e1ect 015 the current increase in windings 1113 and 184.Armature 99 will therefore tend to remain in the position which itoccupied previously and the fiow of 5 current will not be afiectedhy theregulator. By suitable adjustment of sprlng 101 bymeans of screw 188,the regulator may also be so adjusted as to move only when windings 1113and 1114 receive a current corresponding to an excessive arc 10 dropwithin device 18. Such regulator will then be without e1ect on the fiowof current as long as the average arc drop within device 18 remainsnormal.

In the embodiment illustrated in Fig. 6, device 15 121 is omitted anddevice 61 is replaced by a device 129 of the gas or vapor type havingthe anode 132 thereof connected with anode 14 over battery 25 andresistance 135. The cathode 133 of the device is then connected withconductor 18 over 20 windings 183 and 184. The voltage applied to thedevice during the idling or negative period of anode 14 may again beapplied to resistance 135 by short circuiting device 129 over device114. During the period corresponding to curve portion 25 GII in Fig. 8,the grid 131 of device 129 is maintained negative with respect tocathode 133, because grid 131 and battery 122 are herein connected wlthrheostat 1 11 in a manner opposite to that illustrated in Fig. 5 toobtain a grid voltage 30 represented by curve in Fig. 8. At a timecorresponding to point H, K in Fig. 8, grid 131 then becomes positivewith respect to cathode 133 and permits the flow through device 129 o! acurrent by the same process as the flow of cur- 35 rent through device21 in the embodiment illustrated in Fig. 1. Such current is again inproportion to the average value of the arc drop within device 18. At theend of each active period of anode 14, the voltage between anode l32and40 cathode 133 reverses so that device 129 is without current and grid131 is again capable of retardlng the flow of current through device 129untll anode 14 again carries current. The control of regulator 98 lsthus obtained in a manner similar to 45 that described with respect toFig. 5.

In the embodlment illustrated in Fig. 10, winding 94 is directlyconnected wlth line 11 and the adjustment of the cOntrol electrodes isobtained by means of a variable positive direct current bias 50 voltage.In the present embodlment, anode 14 is no longer connected with grid 68over battery 12 and resistance 13 but is connected over a battery 139and a resistance 141 with the grid 138 01 a diScharge device 134 similarto device 81. 55 The cathode 142 of device 1341s connected withconductor 18 over condenser 84, this connection being similar to that 01device 21 et th embodlment illustrated in Fig. 4. The anode 139 ofdevice 134 is energized from battery 82 over a 60 rheostat 131. Theheating circuit of cathode 89 of device 61 includes a regulator 143similar to v regulator 84 but difieringfrom the latter in that regulator143 is provided with a solenoid 144 tending to release the pressureapplied to the 05 carbon pile 88 by a spring 148.

The operation of devices 114 and 121 remain substantially as describedwith respect to the embodiment illustrated in Fig. 5. During the activeperiod of anode 14, grid 138 receives the voltage 70 of battery 139, thearc drop in device 18 and the Voltage condenser 84. When the system isconnected as shown, andanode 14 begins to.carry current durlng a cycleof its operation, condenser 64 13 net charged, and and 133 is morepositive 75 than the value M of Fig. 9 with respect to cathode 52 sothat a comparatively large current flows through device l34 from battery32 over rheostat l31. The flow of such current gradually chargescondenser 64 in such a manner that the condenser plate connected withcathode i42 becomes positive and the plate of such condenser connectedWith conductor l8 becomes negative. The voltage of condenser 64, beingalso inserted in the circuit between cathode I42 and grid 538, causesgrid l38-to become increasingly negative by the amount of the voltage ofcondenser G4. Due to such variation of the voltage of grid i38, thecurrent through device i34 gradually decreases and reatzhes a very smallvalue when the device l34 operates on the lower knee of itscharacteristic at point M in Fig. 9. Such point correSponds to acondenser voltage CE, a bias volt age BP and an arc drop PM. Beyond thepoint M, device i3 i is not entirely non-conductive and a small currentwould continue to flow, thereby slowiy changing the voltage of condenser64. The voltage of the condenser is preierably stabili2ed by permittingthe small current represented by ordinate MN in Fig. 9 to lak overresistance 33, thereby maintaining point M as operating point of devicei 34. The voltage of condenser M, represented by distance 0B, impressedon grid 66 of device 61 in a manner opposite to that previouslydescribed with respect to the embodiment illustrated in Fig. 4. For theparticular value PM of the arc drop in device l6, the condenser 64receives voltage 03 which brings grid 66 to voltage 0E, thereby causingthe flow of a predetermined amount '01 current EF through device 67 frombattery 82 over rheostat 83. Battery 82 also supplies, over rheostat 83,another=,current which fiows over a resistance Ml. thereby bflngs theneutral point of winding 96 to positive potential with respect 'to thepotential of cathode Il. The phase relation between windings 13 and 96'is so chosen that control electrode 93 becomes positive with respect tocathode il at the desired moment to pemiitfloW of current through anodeM. 45 If the arc drop in device l6 increases, the voltage of condenser64 increases thereby bringing the grid 66 of device 67 to the value 0Aless negative with respect to cathode 69. The impedance of device 61 isthus decreased and a .arger cur- 5o rent fiows through such device. Thevoltage drop in rheostat 83 caused by the flow of such current thenincreases which results in a decrease of the flow of current in rheostatM! and therefore in a decrease of the voltage drop in such resistance.55 The positive bias impressed on control electrode 93, which is equalto such voltage drop, is thus decreased and the moment 01 the voltagecycle at which control electrode 93 becomes positive is therebyretarded. As is well known such re- 60 tardation results in a decreaseof the current in device l6. If, however, the increase of the arc dropresults from an increase in the current carried by device i6, solenoid Ireceives an increased current from shunt 41. The action of 5 thesolenoid causes a lasser pressure to be applied to carbon pile 86 andthe resistance of such carbon pile increases. The heating current ofcathode 69 is thereby decreased, such action tending to increase theimpedance of device 61 7 and thus neutralizing the eiect of the changeof Voltage of grid 66. Under such conditions the bias voltage applied tocontrol electrode 33 will not change and the flow of current in devicei6 will not be altered. 7 Although but a few embodiments of the preseutinvention have been illustrated and described, it will be apparent tothose skflled in the art that various changes and modifications may bemade therein without departing from the sp it of the invention or fromthe scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. The combination with an electric current supply circuit, an electriccurrent. load circuit, and an electron discharge device comprising ananode and a cathode interconnecting said circuits and constitutingspaced electrodes for the flow of current therebetween, of meansoperable responSive to variations in the magnitude of the voltage droponly between said electrodes for controlling the operation of saiddevice.

2. The combination with an electric current supply circuit, an eleotriccurrent load circuit. and an electron discharge device comprising ananode and a cathode interconnecting said circuits and c6nstitting spacedelectrodes for the flow of current therebetween, o! meansoperableresponsive to variations in the magnitude of the voltage drop'ofunidirection only between,said electrodes for controlling the operationof said device.

3. The combination with an electric current supply, circuit, a loadcircuit, an electron discharge device comprising an anode and a cathodeinterconnecting said circuits and constituting spaced electrodes for theflow of current therebetWeen, and means operable to control the saidflow of current between said electrodes, of means operable responsive tovariations in the magnitude of the potential diflerence of unidirectiononly between said electrodes for controlling the operation of saiddevice.

4. The combination with an electric current supply circuit, a loadcircuit. an electron discharge device comprising an anode and a cathodeinteonnecting said circuits and coristituting spaced electrodes for theflow of current thereb etween, and means for controlling the flow ofcurrent between said electrodes, of means operabie responsive tovariations in the average value of the voltage drop only between saidelectrodes for controlling the operation of the first said means.

5. The combination with an electric current supply circuit, a loadcircuit, and an electron discharge device comprising an anode and acathode interconnecting said circuits and constituting spaced electrodesfor the flow of current therebetween, of means Operable responsive tovariations in the potential diierence of unidirection only between saidelectrodes for controlling the operatian of said device.

6. The combination with an electric current supply circuit, an electriccurrent load circuit, and an electron discharge device comprising ananode and a cathode interconnecting said circuits and constitutingspaced electrodes for the flow of ourrent therebetween, of meansconnected with said electrodes and operable responsive to the voltagedrop therebetween for aiecting the operation of said device, an electrondiscb.rge device having spaced electrodes includedin said connections ofsaid means operable to limit the response of the latter to periodsduring which current flows beable responsive to the voltage droptherebetween for afiecting the operation of the first said means, and anelectron discharge device included in the connection of the second saidmeans operable to 15 1imit the response thereot to periods during whichcurrent fiows between said electrodes.

8. The combination with an electric current supply circuit, a loadcircuit, and an electron discharge device of the vapor arcing typecomprising 20 an anode and a. cathode interonnecting said circuits andconstituting spaced electrodes for the flow of current therebetween, ofthermal means for producing operating vapor within said device, meansconnected. with said electrodes and 25 operable responsive to thevoltage drop therebetween for afiecting the operation of the first saidmeans. an electron discharge device ci. the vapor type included in theconnection of the second said means operable to limit the response 30thereof to periods during which current flows between said electrodes,means for producing operating vapor within the second said device,thermally actuated means for aifecting the operation of the third saidmeans, and means connected with one of said circuits and operableresponsive to and in dependence upon the magnitude of the currentfiowing therein for causing actuation of the fourth said means.

9. The combination with a polyphase alternat- -40 ing urrent supplycircuit, an electric current load circuit, and an electron dischargedevice comprising a Diurality oi anodes and a cathode interconnectingsaid circuits and constituting spaced electrodes for the flow of currentthrough 45 said device from said suppl circuit to said load circuit, ofmeans for regulating the said flow of current comprising a plurality cfinductors having windings severally included in the connections of theconductors of said supply circuit with said 50 device, meansfor variablyexciting said inductors to thereby vary the inductance thereoi, meansfor energizing the second said means, and means comprising an electrondischarge device having connections with said cathode and with one cf 55saida;iodes operable responsive to and in dependence 'on the voltagedrop therebetween for controlling the operation of the third said means,Whereby the. inductances of sad inductors are varied and the flow ofcurrent through the flrst 60 said device thereby regulated.

10. The combination with a polyphase alternating current supply circuit,an electric current load circuit, and an electron discharge devicecomprising a plurality of anodes and a cathode 65 interconnecting saidcircuits and constituting spaced electrodes for the flow ofcurrentthrough said device from said suppiy circuit to said loadcircuit, of means for regulating the said flow of current comprising aplurality o! inductors 70 having windings 'severally included in theconnections of the conductors of said supply circuit with saiddevice-means including a source of current and an auxiliary winding foreach of said inductors for exciting the latter. means com- 75 prising anelectron discharge device included in the connections of said sourcewith said auxiliary windings operable to control the flow of currentthrough the latter, means for controlling the operation of the secondsaid device, and means comprising an electron discharge device havingcon- 5 nections with said cathode and with one of said anodes operableresponsive to and in dependence on the voltage drop therebetween forcontrolling the fourth said means, whereby the flow of current throughthe said auxiliary windings is varied and the flow of current throughthe first said device thereby regulated.

11. The combination with a polyphase alternating current supply circuit,an electric current load circuit, and an electron discharge devicecomprising a plurality of anodes and a cathode interconnecting saidcircuits and forming spaced electrodes for the flow of currenttherebetween,

. of means for regulating the said flow of current comprising aplurality of inductors having windings severally included in the connctions 01 the conductors of said supply circuit wit said device, meansfor variably exciting said inductors, means for energizing the secondsaid means, means comprising an electron discharge device havingconnections with said cathode and with one of said anodes operableresponsive to and in dependence on the voltage drop therebetween forcontrolling the operation of the third said means to thereby control theoperation of the second said means, and means having connection withsaid load circuit and with the. third said means operable to control thelatter in dependence upon the magnitude of the current flow in said loadcircuit whereby the flow of current through the second said device isregulated in dependence upon the voltage drop between the cathode and ananode of the first device and in dependence of the magnitude of thecurrent supplied therefrom to said load circuit. 40

12. The combination with an alternating current supply circuit, anelectric current load circuit, au electron dlscharge device comprising acathode, a plurality of anodes and a plurality of control electrodesseverally associated with said anodes, means connecting said device withsaid circuits comprising a transformer winding operable to impresspotentials on said anodes during such recurring moments and of such signand magnitude as to cause the flow of current sequentiaily through saidanodes from said supply circuit to said load circuit, means connectedwith said supply circuit and with said control electrodes operable toimpress alternating current potentials on the latter of such phase andduring such recurring moments relative to the potentials impresSed onthe associated said anodes as to control the moments of initiation ofrecurring flow of current through the latter, and means for varying thephase angle of said potentials impressed on said control electrodes,

of means connected with one of said anodes and said cathode operableresponsive to the voltage drop therebetween during periods oi flow o!current therebetween for controlling the operation of the third saidmeans, and means having connection with one of said circuits andoperable in dependence on the current fiowing therein for controllingthe operation of the third-said means.

13. In a control system for electron discharge devices, a supply line,an electron discharge device connected with said lime, an output lineconnected with said device, means responsive to the peak value of thevoltage drop in said device, means for controlling the flow of currentthrough said device, and means controlled by the first said means tocontrol the second said means.

14. In a control system for electron dischalre '10 through said device,and means controlled by the first said means to caus operation of thesecond said means when the voltage drop Within said devlce exceeds apredctermined value.

15. In a control system for electron discharze devices, a supply line,an electron discharge device connected with said line, an output lineconnected with said device, means responsive to the value of the voltagedrop in said device,

means for controlling the operation of said device, and means controlledby the first said means to cause operation of the second said means whenthe voltage drop within said devlce exceeds a predetermined value.

16. In a control system for electron discharge devices, a supply line,an electron discharge device connected with said line, an output lineconnected With said device, means responsive to the value of the voltagedrop in said device,

' means for controlling the operation of said device,

means co-ntrolled by the first said means to control the second saidmeans, and means responsive to the flow of current through said devlceto adjust the operation of the first said means.

17. In a, control system for electrn discharge devices, a supply line,an electron discharge device connected with said line, an output lineconnected with said device, means .responsive to the value of thevoltage drop in said device, means for controlling the operation ofsaiddevice, means controlled by the flrst said means to control the secondsaid means, and means responsive to the flow of current through saiddevice to adjust the operation of the second said means.

18. In a control system for electron discharge devices, a supply line,an electron discharge device connected with said line, an output lineconnected with said device, means responsive to the Value of the voltagedrop in said device, a

circuit breaker in said supply line. and means responsive to operationof the flrst said means for causing operation of said circuit breakcrwhen the voltage drop within said device excceds a predetermined value.

19. In a control system for electron discharge devices, a supply line,an electron discharge device connected with said line, an output line vconnected with said device, means responsive to the value of the voltagedrop in said device,

means producing operating vapor Within said device, and means responsiveto operation of the first said means for causing operation of the secondsaid means when the voltage drop within sa d devise exceeds apredetermined value.

5 20. In a control system for electron discharge devices, a supply line,an electron discharge device connected With said line and havingelectrodes, an otput line connected 'Wlth said device, means connectedWith two of said elec- 7o trodes and receiving current only 'Whencurrent fiows therebetwecn, and means controlled by said means to'regulate the flow of current through said device.

21. In a control system for electron discharge 75 devices, a supplyline, an electron discharge devalue during periods of flow of currentthere- 10 between.

22. In a control system for electron discharge devices, a supply line,an electron discharge device connected With said line and havingelectrodes and current controlling means, an out- 15 put line connectedwith said device, means connected with two of said electrcdes andreceivng current from said supply line only when current -fiows betwecnsaid two of said electrodes, and means controlled by the second saidmeans 20 to control the operation "of said current. controlling means.

23. In a control system for electron discharge devics, a supply line, anelectron discharge device connected with said line and having elec 25trodes, an output line connected with said device, au electron dischargedevlce connectcd Wlth two of the electrodcs of the first said device,the second said devlce receiving current only when current flows betweenthe said two of the 30 electrodes, and. means responsive to the flow ofcurrent through the second said device to control the operation of theflrst said device.

24. In a control system for electron dlscharge devices, a supply line,an electron discharge device connected witl: said line and havingelectrodes, an output lin'e connected With said device, an electrondlscha rge devlce connected with two of said electrodes and receivingcurrent from said supply line only when current flows bein tween thesaid twooi said electrodes, and means responsive to the flow of currentthrough the second said devlce to regulate the flow of current throughthe flrst said device.

25. In combination with an electric current 45 supply circuit, au outputcircuit, and an electron discharge devlce having electroflesconstituting arcing terminals for the flow of current through saiddevlce from said supply circuit to said output circuit, of means forcontrolling the opera 50 tien of said device. means connected With andresponsive to the voltage drop above a predetermined value between twoof said electrodes for controlling the operation of the flrst saidmeans,

and an electron discharge devlce included in the 55 said connection ofthe second said means operable to limit the said responseof the latterto periods during which current flows betvycen the said two of saidelectrodcs.

26. In combination with 'an electric currentfio supply circuit, auoutput circuit, and an electron disoharge device comprising electrodesconstituting arcing terminals for the flow of current through saiddevice from said supply circuit to said output circuit, means forproducing and Ionizing vapor Wlthin said device, means connected withand responsive to the voltage drop above a predetetmird value betweentwo of said electrodes for afiecting the operation of the! flrst saidmeans, and an electron discharge device included in the said connectionof the second said means operabIe to limit the response of the latter toperiods during which current flows between the said two of saidelectrodes'.

27. In combination with an electric current supply circuit, au outputcircuit, an electron discharge device having a plurality of electrodesconstituting arcing terminals for the flow of current through saiddevice from said supply circuit to said output circuit, and meanscomprising an excitation electrode disposed within said device forproducing and maintaining ionized vapor therein, of means connected withand responsive to the voltage drop above a predetermined value betweentwo of said plurality of electrodes for afiecting the 'operation of thefirst said means, and an electron discharge device included in the saidconnection of the second said means operable to limit the responsethereof to periods during which current flows between the said two ofsaid electrodes.

28. In combination with an electric current supply circuit, an outputcircuit, and an electron discharge device comprising electrodesconstituting arcing terminals for the flow of current through saiddevice from said supply circuit to said output circuit, of means forproducing operating vapor within said device, means connected with twoof said electrodes and responsive to the voltage drop therebetween abovea predetermined value for afi'ecting the operation of the flrst saidmeans, an electron discharge device having electrodes included in saidconnections of the second said means operable to limit the response ofthe latter to periods during which current flows between the said two.of said electrodes, means for producing operating vapors within thesecond said electron discharge device, and means connected with saidoutput circuit operable responsive to and in dependence upon themagnitude of the current flowing therein for varying the operation ofthe third said means.

29. In a system of the character described, an alternatingcurrent supplycircuit, au output circuit, au electron dischargedevice comprising acathode, a plurality of anodes and a plurality of control electrodesseverally associated with said anodes, means connecting said device withsaid circuits comprising a transformer winding operable to impresspotentials on said anodes during such recurring moments and of such signand magnitude as to cause the flow of current sequentially through saidanodes from said supply circuit to said output circuit, means connectedwith said supply circuit and with said control electrodes operable toimpress alternating current potentials on the latter of such phaseandmagnitude and during such recurring moments relative to thepotentials impressed on the associated said anodes as to control themoments of initiation of recurring flow of current through the latter,means for varying the phase angle of the said potentials impressed onsaid control electrodes, and means connected with one of said anodes andsaid cathode operable responsive to the voltage drop therebetween duringperiods of flow of current therebetween for controlling the operation ofthe third said means.

30. In a system of the character described, an alternating currentsupply circuit, an output circuit, au electron discharge devicecomprising-a cathode, a plurality of anodes and a pluraiity of controlelectrodes severally associated with said anodes, means connecting saiddevice with said circuits comprising a transformer winding operable toimpress potentials on, said anodes during recurring periods and of suchsign and magnitude asto cause the flow.of current sequentially throughsaid anodesfl irOm' said supply circuit to said output circuit, meansconnected with said supply circuit and said control electrodes operableto impress alternating current potentials on the latter of such phaseand magnitude and during such recurring moments relative to thepotentials impressed on the associated said anodes as to control themoments of initiation of recurring flow of current through the later,means for varying the phase angle of the potentials impressed on saidcontrol electrodes, means connected with one of said anodes and saidcathode and receiving current from said supply circuit in dependenceupon the magnitude of the voltage drop between the said one of saidanodes and said cathode for controlling operation of the third saidmeans, and an electron discharge device included in the said connectionsof the fourth said means operable to 1imit the flow of currenttherethrough to periods during which current flows between the said oneof said anodes and said cathode.

31. The combination with an electron discharge device comprising ananode and a cathode constituting spaced electrodes for the flow ofcurrent therebetween, of means for measuring the voltage drop betweensaid electrodes comprising an indicating device having connectionstherewith and responsive to the voltage drop only therebetween.

32. The combination with an electron discharge device comprising ananode and a cathode constituting spaced electrodes for the flow ofcurrent therebetween, of means for measuring the voltage drop betweensaid electrodes comprising an indicating device having connectiontherewith and responsive to the potential difference only therebetween,and means operable to limit the response of said indicating device t0periods dring which current flows between said electrodes.

33. The combination with an electron discharge device comprising ananode and a cathode constituting spaced electrodes for the flow ofcurrent therebetween, of means for measuring the voltage drop betweensaid electrodes comprising an indicating device having connectiontherewith and responsive to the potential difference only therebetween,and an electron discharge device comprising electrodes included in thesaid connection and operable to limit the response of said indicatingdevice to periods during which current flows between the first saidelectrodes.

34. The combination with an electron discharge device comprising ananode and a cathode constituting spaced electrodes for the flow ofcurrent therebetween, cf means for measuing the voltage drop betweensaid electrodes comprising an indicating device having connectiontherewith and responsive to the potential diierence only therebetween,'and means operable to limit the response. of said indicating device tosaid potential diiierence of unidirection only.

, 35. The combination with an electron discharge device comprising ananode and a cathode constituting spaced electrodes for the flow ofourrent therebetween, of means for measuring the voltage drop betweensaid electrodes comprising an indicating device having connectiontherewith and responsive to the potential difference only therebetween,and an electron discharge de vice having spaced electrodes included insaid connection and operable t0 limit the response of said indicatingdevice to said potential of unidirection only and to periods duringwhich current flows between the first said electrodes.

36. The combination with an electron discharge device comprising ananode and a cathode constituting spaced electrodes for the fiow ofcurrent therebetween, of means for measuring the voltage drop betweensaid electrodes comprising an indicating device having connectiontherewith and responsive to the potential difierence only therebetween,means controlling the response of said indicating device comprlsing anelectron discharge device having spaced electrodes included in saidconnection, and means for regulating the conductivity of the second saidelectron discharge device.

37. The combination with an electron discharge device comprising ananode and a cathode constituting spaced electrodes for the fiow ofcurrent therebetween, of means for controlling the said fiow of current,means for measuring the voltage drop between said electrodes, and meanscomprising an electron discharge device having spaced electrodesconnecting the first said electrodes with the first and second saidmeans and operable to limit the response thereof to the potentialdiference of unidirection only between the first said electrodes.

38. The combination with an electron discharge device comprising ananode and a cathode constituting spaced electrodes for the fiow ofcurrent therebetween, of means for controlling said flow of current,means for measuring the voltage drop between said electrodes, and meanscomprising an electron discharge device having spaced electrodesconnecting the first said electrodes with the first and second saidmeans and operable t limit the response thereof to the potentialdifierence of unidirection only between the first said electrodes and toperiods during which current fiows between the first said electrodes.

39. The combination with an electron discharge device comprising ananode and a cathode constituting spaced electrodes for the fiow ofcurrent therebetween, of means for regulating the voltage drop betweensaid electrodes, means for measuring said voltage drop, and meanscomprising an electron discharge device having spaced electrodesconnecting the first said electrodes with the first and second saidmeans and operable to limit the response thereof to the potentialdifierence of unidirection only between the first said electrodes and toperiods during Which current flows therebetween.

40. The combinationwith an electron discharge device comprlsing an anodeand a cathode constituting spaced lectrodes for the fiow of currenttherebetween, 'of means for measuflng the voltage drop between.saidelectrodes comprising an indicating device having connection with saidelectrodesand responsivetothe potential .difierence only therebetween,means comprising an electron dlscharge device having spaced electrodesincluded in the connection of the first said electrodes with saidindlcating device and operable to limit the response thereof to periodsduring which currentflows between the first said electrodesb and meansoperable in dependence upon theflow of current between the first saidelectrodes for regulatlng the conductivity of the second said electrondischarge device.

41. In a control system for electron dlscharge devlces, a supply fine,an electron discharge device connected with said line, an output lineconnected with said device,means responsive to the value of the voltagedrop only in said device including time delay means operable to retardthe response of said voltage responsive means to variations in the saidvoltage drop, means for controlling the fiow of current through saiddevice, and means controlled by the said voltage responsive means forcontrolling said current controlling means.

42. In a control system for electron discharge devices, a supply lime,an electron discharge device connected with said lime, an output lineconnected with said device, means responsive to the value of the voltagedrop only in said device, means for controlling the fiow of currentthrough said device, and means controlled by said voltage responsivemeans operable t0 cause operation of said current controlling meansincluding time delay means for retarding the operation of said currentcontrolling means in response to variations in the value of said voltagedrop.

43. In a control system for electron discharge devices, a. supply line,an electron discharge device connected with said lino, an output lineconnected with said device, means responsive to the value of the voltagedrop only in said device, means for controlling the fiow ofcurrentthrough said device, means controlled by said voltage responsive meansfor controlling said current controlling means, and time del?.y meansresponsive to the magnitude of the fiow of current through said deviceto adjust the operation of said voltage responsive means, wherby saidoperation is variably adjusted in dependence upon the rate of change ofthe said fiow of current through said device.

44. The combination with an electron discharge device comprisingelectrodes operable for the fiow of current therebetween, of means formeasuring the voltage drop between said electrodes comprising anindicating device responsive to the potential diffrence therebetween,means connected with said indicating device for controlling the responsethereof, and means for controlling the action of said responsecontrolling means to prevent the response of said indicating devicedurng a period immediately preceding a period Of current fiow betweensaid electrodes.

45. The combination with an electron discharge device comprisingelectrodes operable for the fiow of current therebetween, of means formeasuring the voltage drop between said electrodes comprising anindicating device responsive to the potential difierence therebetween,means connected with said indicating device for controlling the responsethereof, and means operable in dependence upon the fiow of currentbetween said electrodes for controlling the action of said responsecontrolling means.

46. The "=cpmbination with an electron dS- charge devicecomprisingelectrodes operable for the'fiow of currnt"therebetween, of means formeasuring the voltage drop between said electrodes comprising anindicating device responslve to the potential difference therebetween,means confprising an auxiliary electron discharge device connected withsaid lndicating device for controlling the response thereof, and meansoperable in dependence upon the flow of current between said electrodesfor controlling the conductlvlty of said auxiliary electron dischargedevice.

'47. The combination with an electron discharge device comprisngelectrodes operable for the fiow of current therebetween, of means formeasuring the average value of the voltage drop between said electrodescomprising an indicatlng device connected with said electrodes andresponsive to the potential dlference therebetwn,

48. The'comblnatlon w1th an electron discharge devlce comprising electrodes operable for the 110w of current therebetween, of means formeasuflng the average value of the voltage drop between said electrcdescomprislng an lndlcating dev lce connected wlth sald electrodes andresponslve to the,.

potential dlflerence therebetween, means con: neCted with.saidlndlcating device for controlling the response thereof, meanscomprisflng an auxlllary electron dlscharge devlce connected with sa1dindlcating device for controlling the response theredt, and meansoperable in dependence upon the flow or current-between safld electmdesfor controflingthe conductivity of said auxliary electron diachargedevlce.

49. The oomblnatlon wioh an electron discharge devlce comprlsinglectrodes operable for the flow of current therebtween, of means formeasuring the average value of the voltage drop between said electrodescomprising an indicating devlce connected with sa:ld electrodes andresponsive to the potential diffrence therebetween, means compfl5ing ana'.uxiliary electron dlscharge devlce connected w1th said indicatingdevice for controlling the response thereot, and means operable independence upon the flow of current between said elctrodes forcontrolling the conductivlty of said auxlllary -discharge device tolim1t the response of sald indicatlng device to periods durlng whlchcurrent flows between said electrodes,

DIDR JOURNEAUX.

